This application is based on and incorporates herein by reference Japanese Patent Application No. 2001-127582 filed on Apr. 25, 2001, Japanese Patent Application No. 2001-131523 filed on Apr. 27, 2001 and Japanese Patent Application No. 2002-008850 filed on Jan. 17, 2002.
1. Field of the Invention
The present invention relates to a motor including a clutch, which couples a rotatable shaft of a rotor to a worm shaft.
2. Description of Related Art
With reference to FIG. 17, one previously proposed motor used, for example, in a power window system includes a motor main body 52, a speed reducing unit 54 and a clutch 55. The motor main body 52 rotates a rotatable shaft 51. The speed reducing unit 54 includes a worm shaft 53 and transmits rotational driving force of the worm shaft 53 to a load side (e.g., a door window glass side of the power window system). The clutch 55 is placed between the rotatable shaft 51 and the worm shaft 53.
With reference to FIG. 18, the clutch 55 includes a driving-side rotator 61, a driven-side rotator 62, a collar 63 and rolling elements 64. The driving-side rotator 61 is connected to a distal end of the rotatable shaft 51 to rotate integrally therewith. The driven-side rotator 62 is integrally connected to a base end of the worm shaft 53. The collar 63 surrounds both the driving-side rotator 61 and the driven-side rotator 62 and is secured to a gear housing 56 of the speed reducing unit 54. The rolling elements 64 are arranged between the driven-side rotator 62 and the collar 63. In the clutch 55, when the driving-side rotator 61 is rotated, each rolling element 64 is rotated together with the driving-side rotator 61 without being clamped between a corresponding control surface 62a of the driven-side rotator 62 and an inner peripheral surface 63a of the collar 63, and the driven-side rotator 62 is engaged with and is rotated by the driving-side rotator 61 in a rotational direction. On the other hand, when rotational force is applied to the driven-side rotator 62 from the load side (worm shaft 53 side) to rotate the driven-side rotator 62, each rolling element 64 is clamped between the corresponding control surface 62a of the driven-side rotator 62 and the inner peripheral surface 63a of the collar 63 to restrain the rotation of the driven-side rotator 62.
Thus, when the rotatable shaft 51 is rotated by the motor main body 52, the rotational driving force of the rotatable shaft 51 is transmitted to the worm shaft 53 through the clutch 55 to raise or lower the window glass. On the other hand, when load (e.g., weight of the window glass or vibrations of the window glass) is downwardly applied to the window glass to apply rotational force to the worm shaft 53, the rotation of the worm shaft 53 is restrained by the clutch 55 to restrain the unexpected downward movement of the window glass.
In order to properly operate the clutch 55, the driving-side rotator 61 and the driven-side rotator 62 are installed such that a rotational axis of the driving-side rotator 61 is aligned with a rotational axis of the driven-side rotator 62. Furthermore, a connecting hole 61a is formed in a central portion of the driving-side rotator 61 to extend in an axial direction. A connecting portion 51a formed in a distal end of the rotatable shaft 51 is press fitted into the connecting hole 61a of the driving-side rotator 61, so that the rotatable shaft 51 and the driving-side rotator 61 are connected to each other to rotate together. Thus, it is required to assemble the motor such that the central axis of the driving-side rotator 61 (connecting hole 61a) and the central axis of the rotatable shaft 51 are aligned with each other.
However, for example, due to a manufacturing error of each corresponding connecting portion, misalignment between the rotational axis of the driving-side rotator 61 and the rotational axis of the rotatable shaft 51 (e.g., tilt of the rotational axis of the rotatable shaft 51 relative to the rotational axis of the driving-side rotator 61, or radial displacement of the rotational axis of the rotatable shaft 51 relative to the rotational axis of the driving-side rotator 61, which extends parallel to the rotational axis of the rotatable shaft 51) can occur. When the misalignment occurs, relatively large radial loads are applied to the connection between the driving-side rotator 61 and the rotatable shaft 51. If the driving-side rotator 61 and the rotatable shaft 51 are rotated at this state, relatively large noises and vibrations are generated at the connection between the driving-side rotator 61 and the rotatable shaft 51.
The present invention addresses the above disadvantages. Thus, it is an objective of the present invention to provide a motor capable of reducing generation of noises and vibrations at a connection between a rotatable shaft of a rotor and a worm shaft.
To achieve the objective of the present invention, there is provided a motor including a motor main body, a speed reducing unit and a coupling means. The motor main body includes a rotatable shaft and rotates the rotatable shaft. The speed reducing unit is connected to the motor main body and includes a worm shaft. The worm shaft is substantially coaxial with the rotatable shaft. The coupling means couples the rotatable shaft with the worm shaft. The coupling means includes a driving-side rotator and a driven-side rotator. The driving-side rotator is connected with the rotatable shaft to rotate integrally with the rotatable shaft. The driven-side rotator is connected with the worm shaft to rotate integrally with the worm shaft and is engageable with the driving-side rotator in a rotational direction. The rotatable shaft includes a connecting portion. The driving-side rotator includes a connecting portion, which is loosely fitted with the connecting portion of the rotatable shaft and is engageable with the connecting portion of the rotatable shaft in the rotational direction to rotate integrally with the connecting portion of the rotatable shaft.
To achieve the objective of the present invention, there is also provided a motor including a motor main body, a brush holder, a speed reducing unit, a coupling means and a positioning means. The motor main body includes a yoke housing. The yoke housing rotatably receives an armature, which includes a rotatable shaft and a commutator. The brush holder is placed in an opening of the yoke housing. The brush holder holds a plurality of brushes in sliding contact with the commutator and includes a bearing, which rotatably supports the rotatable shaft. The speed reducing unit includes a gear housing connected to the yoke housing in such a manner that the brush holder is arranged between the opening of the gear housing and an opening of the yoke housing. The gear housing rotatably receives a worm shaft, which is substantially coaxial with the rotatable shaft. The coupling means couples the rotatable shaft with the worm shaft. The positioning means is placed between the brush holder and the gear housing for positioning the brush holder and the gear housing relative to each other.